The present invention relates to night vision systems, and more particularly, to an illumination system of an active night vision system for an interior cabin of a vehicle.
Night vision systems allow a vehicle occupant to better see objects during relatively low visible light level conditions, such as at nighttime. Night vision systems typically are classified as either passive night vision systems or active night vision systems. Passive systems simply detect ambient infrared light emitted from objects within a particular environment. Active systems utilize a light source to illuminate a target area and subsequently detect infrared light reflected off objects within that area.
Passive systems typically use far-infrared cameras characterized by low resolution and a relatively narrow field-of-view. Such cameras must be located on the vehicle exterior in order to acquire requisite infrared energy in the operating environment. Externally mounted cameras can negatively affect vehicle styling. Far-infrared cameras are also costly to manufacture and generate images that have poor contrast, which can be difficult to interpret.
Active systems provide improved resolution and image clarity over passive systems. Active systems utilize laser or incandescent light sources to generate an illumination beam having near infrared light energy, and charged coupled devices or CMOS cameras to detect reflected infrared light. Active systems commonly deploy a light source external to the vehicle so as to transmit a significant amount of light energy and provide a bright scene for imaging.
Exterior mounted light sources or cameras are undesirable due to risk of damage during a vehicle collision. Night vision components are relatively expensive and, as a result, protection of the components is desired. Also, exterior mounted light sources and cameras are susceptible to theft. Additionally, external mounting of sources and cameras can limit and compromise vehicle design and styling, can be esthetically displeasing, and can increase exposure of the devices to dust and debris. Exposure to dust and debris negatively effects performance of the sources and cameras. When the sources and cameras are dirty, light transmission and reception can be substantially reduced and compromise system performance.
Exterior mounted illumination sources have additional associated disadvantages. A significant disadvantage is that of controlling the wavelength of the illumination beam. Diode lasers are sensitive to changes in temperature. The wavelength of a diode laser output shifts approximately 0.25 nm for every one-degree Celsius temperature change. Since external temperatures vary considerably it is difficult to control the temperature of a diode laser. Such temperature shifts can negatively affect performance of the night vision system. Also, when mounted externally, a risk of exposure to water exists, which can render the laser inoperable. Sealing and housing problems due to thermal energy management may also arise when weatherproofing diode lasers.
Furthermore, in designing a vehicle exterior, the external light source may have to be customized to satisfy styling requirements. Thus it is difficult to achieve commonality for light sources between different vehicles. Designing different light sources for different vehicles is costly.
Thus, there exists a need for an improved illumination system for an active night vision system of a vehicle, which minimizes illuminator system size and power consumption, as well as maximizes illuminator system optical and thermal efficiency.
The present invention provides an illuminator system for an active night vision system for an interior cabin of a vehicle. The illuminator system includes a light source and a beam-forming optic that is optically coupled to the light source. The optic forms an illumination pattern that is directed forward of the vehicle. A housing supports the beam-forming optic along a roofline and window perimeter of the vehicle.
One of several advantages of the present invention is that it provides an optically and thermally efficient illumination system that is located within an interior cabin of a vehicle. By the illumination system being located within the interior cabin, it is easier to control temperature of the light source and there is less risk of exposure to water or condensation.
Another advantage of the present invention is that it provides a light source and receiver mounting arrangement that maintains cleanliness of the light source and the receiver and provides a quality contrast image.
Furthermore, the present invention provides an efficient illumination system that is easy and inexpensive to manufacture and is reliable.
Moreover, the present invention provides a vision system that is compact in design and may be located in various locations within an interior cabin of a vehicle.
The present invention itself, together with further objects and attendant advantages, will be best understood by reference to the following detailed description, taken in conjunction with the accompanying drawing.